Institute of Functional Nano and Soft Materials, Collaborative Innovation Center of Suzhou Nanoscience & Technology, Soochow University , 199 Ren-Ai Road, Suzhou 215123, China.
Department of Electrical Engineering and Computer Sciences, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
ACS Appl Mater Interfaces. 2017 Nov 15;9(45):39758-39770. doi: 10.1021/acsami.7b10948. Epub 2017 Nov 1.
Insulating films are essential in multiple electronic devices because they can provide essential functionalities, such as capacitance effects and electrical fields. Two-dimensional (2D) layered materials have superb electronic, physical, chemical, thermal, and optical properties, and they can be effectively used to provide additional performances, such as flexibility and transparency. 2D layered insulators are called to be essential in future electronic devices, but their reliability, degradation kinetics, and dielectric breakdown (BD) process are still not understood. In this work, the dielectric breakdown process of multilayer hexagonal boron nitride (h-BN) is analyzed on the nanoscale and on the device level, and the experimental results are studied via theoretical models. It is found that under electrical stress, local charge accumulation and charge trapping/detrapping are the onset mechanisms for dielectric BD formation. By means of conductive atomic force microscopy, the BD event was triggered at several locations on the surface of different dielectrics (SiO, HfO, AlO, multilayer h-BN, and monolayer h-BN); BD-induced hillocks rapidly appeared on the surface of all of them when the BD was reached, except in monolayer h-BN. The high thermal conductivity of h-BN combined with the one-atom-thick nature are genuine factors contributing to heat dissipation at the BD spot, which avoids self-accelerated and thermally driven catastrophic BD. These results point to monolayer h-BN as a sublime dielectric in terms of reliability, which may have important implications in future digital electronic devices.
绝缘薄膜在多种电子设备中至关重要，因为它们可以提供电容效应和电场等基本功能。二维（2D）层状材料具有卓越的电子、物理、化学、热学和光学性能，可以有效地提供额外的性能，如柔韧性和透明度。2D 层状绝缘体有望成为未来电子设备的关键组成部分，但它们的可靠性、降解动力学和介电击穿（BD）过程仍未被完全理解。在这项工作中，对多层六方氮化硼（h-BN）的介电击穿过程进行了纳米级和器件级的分析，并通过理论模型研究了实验结果。研究发现，在电场作用下，局部电荷积累和电荷俘获/脱陷是介电击穿形成的起始机制。通过导电原子力显微镜，可以在不同电介质（SiO、HfO、AlO、多层 h-BN 和单层 h-BN）的表面上的几个位置触发击穿事件；当达到击穿时，除了在单层 h-BN 上，所有这些位置的表面上都迅速出现了击穿诱导的凸起。h-BN 具有较高的热导率和单层原子厚度，是在击穿点散热的真正因素，可以避免自加速和热驱动的灾难性击穿。这些结果表明，在可靠性方面，单层 h-BN 是一种卓越的介电材料，这可能对未来的数字电子设备具有重要意义。
